command: change "window-scale" property behavior

This is similar to the "edition" change.

I considered making this go through deprecation, but didn't have a good
idea how to do that. Maybe it's fine, because this is pretty obscure.
But it might break some API users/scripts (it certainly broke
stats.lua), and all I have to say is sorry for that.

DOCS/interface-changes.rst

@@ -67,6 +67,10 @@ Interface changes
       be queried to read the runtime-chosen edition. This is a breaking change
       for any users which expected "edition" to return the runtime-chosen
       edition at default settings (--edition=auto).
+    - the "window-scale" property now strictly returns the value of the option,
+      instead of the actual size of the window. The new "current-window-scale"
+      property needs to be queried to read the value as indicated by the current
+      window size. This is a breaking change.
  --- mpv 0.30.0 ---
     - add `--d3d11-output-format` to enable explicit selection of a D3D11
       swap chain format.

DOCS/man/input.rst

@@ -2026,6 +2026,20 @@ Property list
     (or to be exact, the size the video filters output). ``2`` will set the
     double size, ``0.5`` halves the size.
 
+    See ``current-window-scale`` for the value derived from the actual window
+    size.
+
+    Since mpv 0.31.0, this always returns the previously set value (or the
+    default value), instead of the value implied by the actual window size.
+    Before mpv 0.31.0, this returned what ``current-window-scale`` returns now,
+    after the window was created.
+
+``current-window-scale``
+    The ``window-scale`` value calculated from the current window size. This
+    has the same value as ``window-scale`` if the window size was not changed
+    since setting the option, and the window size was not restricted in other
+    ways. The property is unavailable if no video is active.
+
 ``display-names``
     Names of the displays that the mpv window covers. On X11, these
     are the xrandr names (LVDS1, HDMI1, DP1, VGA1, etc.). On Windows, these
@@ -2731,10 +2745,6 @@ caveats with some properties (due to historical reasons):
     option is for loading playlist during command line parsing. For client API
     uses, you should use the ``loadlist`` command instead.
 
-``window-scale``
-    Returns the current window values if a window exists, and the option value
-    otherwise.
-
 ``profile``, ``include``
     These are write-only, and will perform actions as they are written to,
     exactly as if they were used on the mpv CLI commandline. Their only use is

player/command.c

@@ -2226,34 +2226,28 @@ static int mp_property_video_frame_info(void *ctx, struct m_property *prop,
     return m_property_read_sub(props, action, arg);
 }
 
-static int mp_property_window_scale(void *ctx, struct m_property *prop,
-                                    int action, void *arg)
+static int mp_property_current_window_scale(void *ctx, struct m_property *prop,
+                                            int action, void *arg)
 {
     MPContext *mpctx = ctx;
     struct vo *vo = mpctx->video_out;
     if (!vo)
-        goto generic;
+        return M_PROPERTY_UNAVAILABLE;
 
     struct mp_image_params params = get_video_out_params(mpctx);
     int vid_w, vid_h;
     mp_image_params_get_dsize(&params, &vid_w, &vid_h);
     if (vid_w < 1 || vid_h < 1)
-        goto generic;
+        return M_PROPERTY_UNAVAILABLE;
 
-    switch (action) {
-    case M_PROPERTY_GET: {
-        int s[2];
-        if (vo_control(vo, VOCTRL_GET_UNFS_WINDOW_SIZE, s) <= 0 ||
-            s[0] < 1 || s[1] < 1)
-            goto generic;
-        double xs = (double)s[0] / vid_w;
-        double ys = (double)s[1] / vid_h;
-        *(double *)arg = (xs + ys) / 2;
-        return M_PROPERTY_OK;
-    }
-    }
-generic:
-    return mp_property_generic_option(mpctx, prop, action, arg);
+    int s[2];
+    if (vo_control(vo, VOCTRL_GET_UNFS_WINDOW_SIZE, s) <= 0 ||
+        s[0] < 1 || s[1] < 1)
+        return M_PROPERTY_UNAVAILABLE;
+
+    double xs = (double)s[0] / vid_w;
+    double ys = (double)s[1] / vid_h;
+    return m_property_double_ro(action, arg, (xs + ys) / 2);
 }
 
 static void update_window_scale(struct MPContext *mpctx)
@@ -3328,7 +3322,7 @@ static const struct m_property mp_properties_base[] = {
     M_PROPERTY_ALIAS("dheight", "video-out-params/dh"),
     M_PROPERTY_ALIAS("width", "video-params/w"),
     M_PROPERTY_ALIAS("height", "video-params/h"),
-    {"window-scale", mp_property_window_scale},
+    {"current-window-scale", mp_property_current_window_scale},
     {"vo-configured", mp_property_vo_configured},
     {"vo-passes", mp_property_vo_passes},
     {"current-vo", mp_property_vo},
@@ -3449,7 +3443,8 @@ static const char *const *const mp_event_property_change[] = {
       "demuxer-cache-duration", "demuxer-cache-idle", "paused-for-cache",
       "demuxer-cache-time", "cache-buffering-state", "cache-speed",
       "demuxer-cache-state"),
-    E(MP_EVENT_WIN_RESIZE, "window-scale", "osd-width", "osd-height", "osd-par"),
+    E(MP_EVENT_WIN_RESIZE, "current-window-scale", "osd-width", "osd-height",
+      "osd-par"),
     E(MP_EVENT_WIN_STATE, "window-minimized", "display-names", "display-fps",
       "fullscreen", "window-maximized"),
     E(MP_EVENT_CHANGE_PLAYLIST, "playlist", "playlist-pos", "playlist-pos-1",

player/lua/stats.lua

@@ -506,7 +506,7 @@ local function add_video(s)
     if append(s, r["w"], {prefix="Native Resolution:"}) then
         append(s, r["h"], {prefix="x", nl="", indent=" ", prefix_sep=" ", no_prefix_markup=true})
     end
-    append_property(s, "window-scale", {prefix="Window Scale:"})
+    append_property(s, "current-window-scale", {prefix="Window Scale:"})
     append(s, format("%.2f", r["aspect"]), {prefix="Aspect Ratio:"})
     append(s, r["pixelformat"], {prefix="Pixel Format:"})